The present invention relates to a projector having a construction which prevents leakage of air which has been heated up by light from a lamp, or by heat generated by the lamp, from a wire lead out aperture which is provided in a lamp unit.
There is a per se known prior art projector which irradiates light from a lamp upon an image display device, such as a digital micro mirror device (DMD) or a liquid crystal display device, and which projects an image displayed upon this image display device upon a screen.
With this type of projector, the super high voltage mercury lamp which is used as the light source attains an extremely high temperature, due to generation of heat. Furthermore, it is necessary to keep the temperature of the lamp constant, in order to ensure that the lamp emits light at good efficiency. Thus, with a prior art projector, in order to cool the lamp with good efficiency, the lamp is housed in a lamp casing made from a plastic resin. And the lamp is cooled by impact of an air stream which is blown against the lamp from a fan.
Furthermore, with a prior art type projector, as described in Japanese Laid-Open Patent Publication 2004-12827, at least a portion of the lamp casing (lamp housing) is made from metal. And, in some cases, an air flow is furnished by the fan and flows along the metallic portion of the lamp housing.
In a prior art type projector, a wiring lead out aperture is provided in the lamp casing. And wiring connected to the electrical power terminals of the lamp is led out from this aperture, so that electrical power for illuminating the lamp may be supplied via this wiring. At this time, in order to prevent the covering of this wiring being softened or deteriorated by the heat of the lamp, normally, the aperture for bringing out the wiring is provided in the neighborhood of the electrode terminals of the lamp.
With a projector of the structure described above, as with the projection type display device described in Japanese Laid-Open Patent Publication 2004-12827, if the lamp case is made from metal, and the aperture for bringing out the wiring is provided in the neighborhood of the electrode terminals of the lamp, then it is necessary to ensure clearances and creepage distances and an adequate perpendicular distance between the lamp casing and the electrode terminals.
Furthermore, along with revision of the UL standard, for all of the plastic resin components used in the projector which are exposed to direct UV radiation from the lamp used as the light source, it is necessary to utilize a material which conforms to the standard for ultraviolet radiation resistance. Since, when light leaks out from the lamp casing (lamp housing), it strikes against the chassis of the projector or against peripheral components, accordingly it is necessary to utilize a plastic resin which conforms to the standard for ultraviolet radiation resistance for the chassis and these components as well.
However, such a plastic resin which conforms to the standard for ultraviolet radiation resistance is quite high in cost. Due to this, if such a plastic resin which conforms to the standard for ultraviolet radiation resistance is used for the chassis of the projector or for components thereof, the overall cost is increased. Furthermore, if a construction in which light can escape from the lamp casing is employed, then, since air which has been heated up by the heat of the lamp also leaks out, accordingly there is a fear that this hot air may apply heat to the chassis of the projector or to other components thereof, and may cause them to be softened or deformed.
The object of the present invention is to provide a projector which has a construction with which it is possible to ensure clearances and creepage distances between the lamp and the lamp casing, and with which light and air do not leak out from the wire lead out aperture of the lamp casing.